French investigators say they have identified one of the seven attackers who killed at least 129 people in Paris on November 13 in the deadliest terrorist attack in Europe since the 2004 Madrid train bombings killed 191.
Omar Ismail Mostefai, a 29-year-old French citizen of Algerian origin, had a history of petty crime and was known to have been radicalized.
He was identified after investigators found a severed finger at the site of one of the attacks, the French AFP news agency reports.
Six people close to Mostefai have reportedly been detained, including his father, brother, and sister-in-law.
The November 13 coordinated assaults targeted six different sites across the French capital, including the Bataclan concert hall, France's national stadium north of Paris, restaurants, and bars.
Prosecutors say seven heavily armed attackers wearing explosive belts died in the attacks. It is not known if other attackers escaped. More than 350 people were also wounded, with 99 of them in critical condition.
Islamic State (IS) militants claimed responsibility for the attacks, referring to French air strikes against the extremist group in Syria and Iraq.
Paris prosecutor Francois Molins said on November 14 that “three coordinated teams of terrorists,” including seven suicide bombers wearing vests containing triacetone triperoxide (TATP), were probably behind this "barbaric act." TATP is a type of explosive that can be made with easily available chemicals and is difficult to detect.
"We have to find out where they came from... and how they were financed," Molins said.
He added that a car with Belgian registration found at the Bataclan had been rented by a Frenchman living in Belgium.
Officials say another car used by the gunmen has been found in an eastern suburb with several Kalashnikov rifles inside.
The investigation has widened across Europe, with Belgian police arresting three men for suspected links to the Paris attacks.
German officials said a man arrested in the southern state of Bavaria earlier this month after guns and explosives were found in his car may also be linked to the attacks.
The Serbian Interior Ministry said the holder of a Syrian passport found next to the body of one of the attackers outside the Stade de France stadium "was registered on the Presevo border crossing on October 7 this year, where he formally sought asylum." The Presevo border crossing separates Serbia from Macedonia.
Greek authorities had confirmed that the document had been used to travel through the island of Leros on October 3.
WATCH: Migrants and refugees arriving at the Macedonian-Serbian border crossing of Tabanovce were horrified to learn of the November 13 terrorist attacks in Paris. As they travel through Europe, they now fear becoming targets of a backlash and worry it will become harder to claim asylum.
Meanwhile, France has begun three days of national mourning.
President Francois Hollande has imposed a state of emergency and canceled his plans to attend a summit of the Group of 20 (G20) major economies starting in Turkey later on November 15.
A special service for the families of the victims and survivors will be held at Paris's Notre Dame Cathedral.
Speaking on November 15 in Turkey, where he arrived for a G20 summit, U.S. President Barack Obama described the assaults as "an attack on the civilized world" and said the United States would work with France to hunt down those responsible.
Meanwhile, the head of the world's top Islamic body condemned "in the strictest terms" the Paris gun and bomb attacks and called for “a concerted joint action to combat the scourge of terrorism which has become the arch enemy of humanity at large."
Iyad Madani, the secretary-general of the Jeddah-based Organization of Islamic Cooperation, voiced his "firm rejection of any terrorist act" that undermines "universal human values including the values of freedom and equality that France has consistently promoted."
With reporting by AFP, AP, and lefigaro.fr